The second effect is that neutrinos are expected, because of their
finite masses, to have a non-zero
magnetic moment [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]}, [9]},
so that propagation in galactic and cosmic magnetic fields [10]}, [11]} rotates their spins with respect to their momenta, again allowing neutrinos and antineutrinos to have an amplitude to be flipped in helicity, a point first noted in Ref. [3]}.
The recent XENON1T report of the observation of an excess of low energy electron
events [13]} has
triggered interest in the possibility that a sizable
magnetic moment of solar neutrinos, of order \(\sim 1.4-2.9 \times 10^{-11} \mu _B \, (\equiv \mu _{1T})\) , where \(\mu _B\)  is the Bohr magneton, could account for these excess events [14]}, [15]}.
